| 摘要 |
PURPOSE:To minimize changes in the current density distribution of an electron beam having a linear cross section by forming the electron gun by using a hot cathode, an accelerating electrode and a lead-out electrode having a rectangular hole which absorbs part of the electrons and admit the remaining electrons so that they are introduced toward the accelerating electrode. CONSTITUTION:An electron gun 1 for an electron beam device for producing an electron beam having a linear cross section is constituted of a hot cathode 2 having a cathode 23 made by impregnating a porous tungsten mother material with an alkaline earth metal oxide, a lead-out electrode 3 having a rectangular hole 24 and an accelerating electrode 4 having an electron beam hole 25. A low positive electric potential and a high positive electric potential relative to the electric potential of the hot cathode 2, are respectively applied to the lead-out electrode 3 and the accelerating electrode 4. The rectangular hole 24 of the lead-out electrode 3 absorbs part of the discharged electrons and admits the other electrons so that they are introduced toward the accelerating electrode 4 before being caused to bump against an object 12 to be treated. As a result, the current density of the beam can be increased and changes in the distribution of the current density can be minimized, thereby obtaining a stable electron beam with a high luminance. |
